The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent the work is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Generally, an optical pickup unit (OPU) includes a collimator to collimate a light beam emitted from a light source. Further, the OPU includes an objective lens to focus the collimated light beam onto an optical disc.